How to solve "TypeError : Error #1010 : A term is undefined and has no properties

How to solve "TypeError : Error #1010 : A term is undefined and has no
properties

I'm working on a mp3 player using ActionScript 3.0 , below is my code:
var my_songs:XMLList;
var my_total:Number;
var my_sound:Sound;
var my_channel:SoundChannel;
var current_song:Number = 0;
var myXMLLoader:URLLoader = new URLLoader();
myXMLLoader.load(new URLRequest("music/shakira.xml"));
myXMLLoader.addEventListener(Event.COMPLETE, processXML);
function processXML(e:Event):void
{
var myXML:XML = new XML(e.target.data);
my_songs = myXML.SONG;
my_total = my_songs.length();
playSong(0);
}
function playSong(mySong:Number):void
{
var myTitle = my_songs[mySong]. @ TITLE;
var myArtist = my_songs[mySong]. @ ARTIST;
var myURL = my_songs[mySong]. @ URL;//title_txt.text = myTitle;
// artist_txt.text = myArtist;
if (my_channel)
{
my_channel.stop();
}
my_sound = new Sound();
my_sound.load(new URLRequest(myURL));
my_channel = my_sound.play();
}
//next_btn.addEventListener(MouseEvent.CLICK, onNext);
// function onNext(e:MouseEvent):void{
// current_song++;
//if (current_song>=my_total){
// current_song=0;
// }
// playSong(current_song);
// }
And I have an output error :
TypeError: Error #1010: A term is undefined and has no properties.
at musicplayer_fla::MainTimeline/playSong()
at musicplayer_fla::MainTimeline/processXML()
at flash.events::EventDispatcher/dispatchEventFunction()
at flash.events::EventDispatcher/dispatchEvent()
at flash.net::URLLoader/onComplete()
Could anyone,please help me find what the error is and fix it? Thank you
so much, it's urgent tofor me to fix this problem.